Contents

Introduction

Geothermal regions around the world provide hot water and steam that can
be used to provide heat for homes and businesses and/or to generate
electricity. Typically, naturally occurring hot springs are directly
tapped to extract hot water and steam.
In regions where there is hot rock, but no hot springs, geothermal energy
can be produced by by injecting water into hot rock formations and
extracting the water that is heated through contact with the formation.

Enhanced Geothermal Systems (ESG) are a new type of geothermal power
technology that enhances water flow in hot rock reservoirs by injecting
cold water under pressure in order to increase the permeability,
and hence the flow of water, in the reservoir.
Injecting water under pressure causes naturally occurring fractures to open.
The opening of the fractures can be detected by seismometers
as microearthquakes. A microearthquake is defined as a very
low intensity earthquake (i.e., with a magnitude of 3 or less on the
Richter scale).

Visualization of Microearthquakes

Generally, earthquake locations are pinpointed on maps even though the
epicenter of earthquakes are not at ground surface. In the case of
microearthquakes occurring as a result of enhanced geothermal energy
production, it is interesting to look at the 3D distribution of
microearthquakes.
The images below show microearthquakes that occurred at The Geysers
geothermal field in California between October 18 and November 17, 2009.
The largest microearthquake that occurred during this period had a
magnitude of 2.82 and occurred on November 16.
The radii of the glyphs are proportional to the magnitude of the
microearthquakes. Note that the scaling of the glypyhs varies from
image to image; the larger the number of earthquakes, the smaller the
scaling factor used.

day view, click to enlarge

week view, click to enlarge

month view, click to enlarge

Making Microearthquake Data From The Geysers Publicly Accessible

The Earth Science Division at Lawrence Berkeley National Laboratory has
developed a Web site to provide information about enhanced geothermal systems
and induced seismicity, as well as near real-time data on microearthquakes
occurring at The Geysers. See the For More Information
section below for links to this information.

In order to provide 3D visualizations of the microearthquake data, we
installed the visualization and analysis package,
VisIt, on the server that receives
and archives the microearthquake data from The Geysers.
To generate the 3D visualizations shown above, a PHP script calls VisIt to run in command line mode; a Python script is used to control different aspects of the visualization.
Though it is not possible for the user to interact with the image generated
by VisIt, different viewing angles are available by selecting the desired
orientation.

Future Plans

We plan to implement the same technology used to create visualizations of
microearthquakes at The Geysers to create visualizations of microearthquakes
at Desert Peak & Brady's Hot Springs, also in California.
In addition, we plan to install VisIt on a workstation at the
Desert Peak/Brady's Hot Springs site in order to provide real-time,
3D visualizations of the earthquake data for viewing by the geothermal
plant operators.